3-D Woven Active Fiber Composite

ABSTRACT

A three-dimensional woven active fiber composite is disclosed. The composite includes a plurality of actuating fibers configured in a three-dimensional arrangement. The composite further includes a plurality of conductive wire electrodes that are woven through the plurality of actuating fibers. The electrodes may be configured into two dimensional electrode mats that are spaced apart along the length of the composite. Filler fibers may be used between adjacent electrode mats to help reinforce the composite. A sleeve member can also be used to help provide compressive containment for the actuating fibers and conductive wire electrodes.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. Pat. No. ______, currentlyU.S. application Ser. No. 12/969,730, entitled “3-D Woven Active FiberComposite,” filed on Dec. 16, 2010, and allowed on Jan. 17, 2013, thecontents of which are hereby incorporated by reference in its entiretyinto this disclosure.

BACKGROUND

The embodiments relate to piezoelectric materials and in particular toactive fiber composites comprising piezoelectric materials.

Piezoelectric materials can be arranged as fibers and combined withelectrodes to yield active fiber composites. Hagood, IV et al. (U.S.Pat. No. 5,869,189) teaches composites for actuating or sensingdeformation. The piezoelectric fibers are arranged in a parallel arraywith adjacent fibers separated by a soft polymer. Hagood further teachesflexible conductive material extending along the axial extensions of thefibers for imposing or detecting an electrical field.

Wilkie (U.S. Pat. No. 6,629,341) is directed to a method of fabricatinga piezoelectric composite apparatus. Wilkie teaches a piezoelectricmacro-fiber composite comprising a PZT-5 piezoelectric ceramic materialformed into a wafer.

Chiang et al. (U.S. patent application publication number 2006/0102455)teaches an electrochemical actuator. The electrochemical actuatorincludes a support system including both top and bottom fibers. The topand bottom fibers are inert and are used to support the electrochemicalactuators.

SUMMARY

Embodiments of a three dimensional woven active fiber composite aredisclosed. In some embodiments, the woven active fiber composite mayinclude various directions such as a longitudinal direction extendingalong a length of the woven active fiber composite, a lateral directionextending along a width of the woven active fiber composite and avertical direction extending along a height of the woven active fibercomposite. In some embodiments, the woven active fiber composite canalso include a plurality of actuating fibers with each actuating fiberextending in the longitudinal direction. The woven active fibercomposite may also include a first group of actuating fibers from theplurality of actuating fibers that are spaced apart from one another inthe lateral direction as well as a second group of actuating fibers fromthe plurality of actuating fibers that are spaced apart from one anotherin the lateral direction. In some cases, the second group of actuatingfibers may be spaced apart from the first group of actuating fibers inthe vertical direction. The woven active fiber composite can alsoinclude a conductive wire electrode configured to transfer electricalenergy to and from the first group of actuating fibers and the secondgroup of actuating fibers. Moreover, in some cases, the conductive wireelectrode is in contact with at least one actuating fiber from the firstgroup of actuating fibers and the conductive wire electrode is incontact with at least one actuating fiber from the second group ofactuating fibers.

In some embodiments, the woven active fiber composite can includevarious directions such as a longitudinal direction extending along alength of the woven active fiber composite, a lateral directionextending along a width of the woven active fiber composite and avertical direction extending along a height of the woven active fibercomposite. In some embodiments, the woven active fiber composite canalso include a plurality of actuating fibers with each actuating fiberextending in the longitudinal direction. In some cases, the plurality ofactuating fibers may be spaced apart in the lateral direction and thevertical direction. In some embodiments, the woven active fibercomposite can include a plurality of conductive wire electrodesconfigured to transfer electrical energy to and from the plurality ofactuating fibers. Moreover, in some cases, a first set of conductivewire electrodes are woven in a planar configuration between theplurality of actuating fibers such that the planar configuration ofconductive wire electrodes extends in the lateral direction and thevertical direction.

In some embodiments, the woven active fiber composite includes variousdirections such as a longitudinal direction extending along a length ofthe woven active fiber composite and a radial direction that isperpendicular to the longitudinal direction. The radial direction mayextend from an axial center line of the woven active fiber composite.The woven active fiber composite can also include a plurality ofactuating fibers such that each actuating fiber extends in thelongitudinal direction and such that the plurality of actuating fibersare spaced apart in the lateral direction and the vertical direction.The woven active fiber composite can also include a plurality ofconductive wire electrodes configured to transfer electrical energy toand from the plurality of actuating fibers such that the plurality ofconductive wire electrodes are interwoven with the plurality ofactuating fibers. In some cases, the woven active fiber composite caninclude a sleeve member extending in the longitudinal direction, wherethe sleeve member is configured to wrap around an outer periphery of thewoven active fiber composite in order to provide containment of thewoven active fiber composite in the radial direction.

In one aspect, a woven active fiber composite includes a longitudinaldirection extending along a length of the woven active fiber composite,a lateral direction extending along a width of the woven active fibercomposite, and a vertical direction extending along a height of thewoven active fiber composite. The woven active fiber composite alsoincludes a plurality of actuating fibers, each actuating fiber extendingin the longitudinal direction, where the plurality of actuating fibersare spaced apart from one another in the lateral direction and thevertical direction. The fiber composite also includes a first set ofconductive wire electrodes woven between the plurality of actuatingfibers and a second set of conductive wire electrodes woven between theplurality of actuating fibers, where the first set of conductive wireelectrodes is spaced apart from the second set of conductive wireelectrodes in the longitudinal direction. The fiber composite alsoincludes a plurality of filler fibers woven between the actuatingfibers, where the plurality of filler fibers are disposed between thefirst set of conductive wire electrodes and the second set of conductivewire electrodes.

Other systems, methods, features and advantages of the invention willbe, or will become, apparent to one of ordinary skill in the art uponexamination of the following figures and detailed description. It isintended that all such additional systems, methods, features andadvantages be included within this description and this summary, bewithin the scope of the invention, and be protected by the followingclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention can be better understood with reference tothe following drawings and description. The components in the figuresare not necessarily to scale, emphasis instead being placed uponillustrating the principles of embodiments of the invention. Moreover,in the figures, like reference numerals designate corresponding partsthroughout the different views.

FIG. 1 is an isometric view of an embodiment of a three-dimensionalwoven active fiber composite;

FIG. 2 is an enlarged view of an embodiment of a portion of athree-dimensional woven active fiber composite;

FIG. 3 is a top-down view of an embodiment of a portion of athree-dimensional woven active fiber composite;

FIG. 4 is a cross-sectional view of an embodiment of a three-dimensionalwoven active fiber composite indicating the woven pattern of a set ofconductive wire electrodes;

FIG. 5 is an isometric view of an embodiment of a three-dimensionalwoven active fiber composite indicating the repeated woven pattern ofconductive wire electrodes;

FIG. 6 is a cross-sectional view of an embodiment of a three-dimensionalwoven active fiber composite indicating the woven pattern of a pluralityof filler fibers;

FIG. 7 is a cross-sectional view of an embodiment of a several actuatingfibers;

FIG. 8 is an isometric view of an embodiment of a three-dimensionalwoven active fiber composite including a sleeve member;

FIG. 9 is a cross-sectional view of an embodiment of a three-dimensionalwoven active fiber composite including a sleeve member;

FIG. 10 is an isometric view of an embodiment of a roundedcross-sectional shape for a three-dimensional woven active fibercomposite;

FIG. 11 is an isometric view of an embodiment of a star-likecross-sectional shape for a three-dimensional woven active fibercomposite;

FIG. 12 is an isometric view of an embodiment of a hexagonalcross-sectional shape for a three-dimensional woven active fibercomposite;

FIG. 13 is an isometric view of an embodiment of an annularcross-sectional shape for a three-dimensional woven active fibercomposite; and

FIG. 14 is an isometric view of an embodiment of a rectangularcross-sectional shape with a hollow core for a three-dimensional wovenactive fiber composite.

DETAILED DESCRIPTION

FIGS. 1 and 2 illustrate an isometric view of an exemplary embodiment ofa three-dimensional woven active fiber composite 100, hereby alsoreferred to as composite 100. FIG. 3 illustrates a top-down view of anembodiment of composite 100. The term “active fiber composite” as usedthroughout the specification and claims refers to a composite materialformed by combining actuating fibers with one or more sets ofelectrodes. The term “active fiber composite” is not intended to belimited to particular actuating materials. Furthermore, the term “activefiber composite” is not intended to be limited to particular uses.Active fiber composites as discussed throughout this detaileddescription may be used in various applications, including, but notlimited to: energy harvesting applications, structural controlapplications, as well as other types of applications. In one example,one-time use lithium batteries could be replaced with energy harvestingactive fiber composite materials to supply power in various electricallypowered devices. In another example, active fiber composites could beused in structural control applications. Examples of structural controlapplications include, but are not limited to: dynamic twist controlapplications, structural acoustic control applications, radiated noisereduction applications, as well as other applications.

A woven active fiber composite can include fibers formed of one or morepiezoelectric materials. Examples of various piezoelectric materialsinclude, but are not limited to: natural and man-made piezoelectriccrystals such as Berlinite, cane sugar, Quartz, Rochelle salt, Topaz,Tourmaline Group Minerals, Gallium orthophosphate, and Langasite.Additionally, other piezoelectric materials include man-made ceramicssuch as Barium titanate, Lead titanate, Lead Zirconate titanate,Potassium niobate, Lithium niobate, Lithium tantalite, Sodium tungstate,as well as polymers such as polyvinyllidene fluoride (PVDF). It shouldbe understood that this list is not meant to be exclusive and othertypes of piezoelectric materials could also be used to make actuatingfibers for an active fiber composite.

Referring to FIGS. 1 through 3, composite 100 includes a plurality ofactuating fibers 102. In this exemplary embodiment, actuating fibers 102are fibers made of lead zirconate titanate, hereby referred to as PZT.In other embodiments, actuating fibers 102 could be made of otherpiezoelectric materials, as previously discussed. Actuating fibers madeof PZT are known and are currently produced by the VSSP process byAdvanced Cerametrics, Inc. In other cases, actuating fibers 102 may bemade of piezoelectric materials that are spun into a yarn to provide acontinuous desired length. For example, actuating fibers 102 may be madeof many short PZT filaments that are spun into a yarn to provide acontinuous desired length for actuating fibers 102.

Generally, a woven active fiber composite can comprise any number ofactuating fibers. For purposes of clarity, the current embodimentincludes a relatively small number of actuating fibers. In particular,the current embodiment includes approximately 16 actuating fibers. Inother embodiments, however, a woven active fiber composite can include amuch larger number of actuating fibers. In other embodiments, a wovenactive fiber composite can include N actuating fibers, where N is anynumber equal to or greater than 1.

Woven active fiber composite 100 can be associated with one or moredirections. The term “longitudinal direction” as used throughout thisdetailed description and in the claims refers to a direction that issubstantially parallel with a length of woven active fiber composite100. Likewise, the term “lateral direction” as used throughout thisdetailed description and in the claims refers to a direction that isgenerally parallel with a width of woven active fiber composite 100. Inother words, the lateral direction is generally perpendicular to thelongitudinal direction. In addition, the term “vertical direction” asused throughout this detailed description and in the claims refers to adirection that is perpendicular to both the longitudinal and lateraldirections. It should be understood that woven active fiber composite100 may be configured to bend, twist or otherwise deform in someembodiments. In such cases, the designations of a longitudinaldirection, lateral direction, and vertical direction should beunderstood to mean generally in a direction along the length, width andheight, respectively, of composite 100. Furthermore, the terms may beused locally to describe a direction generally parallel with a length ofa particular actuating fiber or a direction generally parallel with awidth of a particular actuating fiber or a direction generally parallelwith a height of a particular actuating fiber.

Actuating fibers of a woven active fiber composite are configured toundergo various types of actuation. In some embodiments, actuatingfibers may be configured to undergo d31 actuation, which is actuation ina lateral direction of a woven active fiber composite. In otherembodiments, actuating fibers may be configured to undergo d33actuation, which is actuation in the axial direction. The term “axialdirection” as used throughout this detailed description and in theclaims refers to a direction that is oriented along the length of anactuating fiber. In many cases, the axial direction may be substantiallyparallel to a longitudinal direction of a woven active fiber composite.As actuating fibers undergo actuation in the axial direction, actuatingfibers may expand or contract in the axial direction, depending on thepolarity of the voltage applied to the actuating fibers. As a pluralityof actuating fibers undergo actuation, this arrangement results inlengthwise expansion or contraction of the entire woven active fibercomposite in a generally longitudinal direction.

Generally, actuating fibers in a three-dimensional woven active fibercomposite can be configured in any three-dimensional arrangement. Insome cases, actuating fibers can be arranged in a grid-like manner, withadjacent actuating fibers spaced apart from one another in the lateraldirection and the vertical direction. In particular, in some cases,actuating fibers may be approximately evenly spaced apart from oneanother in both the lateral and vertical direction. In other cases,however, the spacing between adjacent actuating fibers can be irregular.Moreover, in other embodiments, actuating fibers may not be organizedinto regular rows or columns in the lateral and vertical directions.

Actuating fibers 102 may include first group of actuating fibers 120,second group of actuating fibers 122, third group of actuating fibers124 and fourth group of actuating fibers 126. In one embodiment, eachgroup of actuating fibers comprises four actuating fibers that arespaced apart from one another in the lateral direction. In some cases,the actuating fibers within a group may have approximately the samevertical position with respect to composite 100. In addition, each groupis spaced apart from adjacent groups in the vertical direction. In otherwords, actuating fibers within a group are spaced apart vertically fromactuating fibers in an adjacent group. For example, in one embodiment,first group of actuating fibers 120 comprise a top row of actuatingfibers for composite 100. Second group of actuating fibers 122 comprisesa second row that is disposed below first group of actuating fibers 120.Each actuating fiber within first group of actuating fibers 120 isvertically spaced apart from the actuating fibers within second group ofactuating fibers 122. In a similar manner, third group of actuatingfibers 124 comprises a third row that is disposed below second group ofactuating fibers 122. Likewise, fourth group of actuating fibers 126comprises a fourth row that is disposed below third group of actuatingfibers 124.

Actuating fibers 102 have been divided into groups comprisingplanar-like configurations of actuating fibers that are stacked in thevertical direction for purposes of describing the arrangement ofactuating fibers 102. It will be understood that this configuration ofactuating fibers could also be described as comprising planar-likeconfigurations of actuating fibers that are spaced apart in the lateraldirection. Furthermore, it should be understood that in otherembodiments, it may not be possible to organize actuating fibers intodistinct planar-like configurations that are spaced in the vertical,lateral and/or diagonal directions. In other embodiments, for example,actuating fibers could be arranged in irregular configurations. In thesesituations, however, it may still be possible to find groups ofactuating fibers that are spaced apart from one another in the verticaldirection.

A woven active fiber composite may also include a plurality ofelectrodes. Generally, any type of electrodes may be used. In someembodiments, printed electrodes can be used. In an exemplary embodiment,conductive wire electrodes may be used.

Generally, any type of conductor may be used for a conductive wireelectrode. Examples of conductive materials include, but are not limitedto: metallic conductors and non-metallic conductors. Examples ofmetallic conductors include, but are not limited to: copper, silver,gold, and aluminum as well as other materials. Examples of non-metallicconductors include, but are not limited to: graphite, salt solutions,and plasmas. Typically, a conductive material may be used that can beformed into a wire. In one embodiment, the conductive wire may be analuminum wire. However, in other embodiments, another type of conductivewire could be used. It should be understood that this list is not meantto be exclusive and other types of conductive materials could also beused as electrodes for an active fiber composite.

Woven active fiber composite 100 can include a plurality of conductivewire electrodes 104. In some embodiments, a conductive wire electrodemay comprise a single filament. In other embodiments, a conductive wireelectrode may comprise a multi-filament braid. As previously discussed,in one embodiment, conductive wire electrodes 104 may be made ofaluminum wire.

Conductive wire electrodes 104 may be oriented in any direction withrespect to actuating fibers 102. In some cases, conductive wireelectrodes 104 can be disposed in a generally parallel direction withactuating fibers 102. In other cases, conductive wire electrodes 104 canbe disposed in a generally perpendicular direction with actuating fibers102. In still other cases, conductive wire electrodes 104 can bedisposed in another direction with respect to actuating fibers 102. Inan exemplary embodiment, conductive wire electrodes 104 are disposed ina generally perpendicular direction with actuating fibers 102. In otherwords, the length of conductive wire electrodes 104 extends in a lateraldirection. With this arrangement, a single conductive wire electrode mayoverlap with a plurality of actuating fibers 102.

Conductive wire electrodes 104 can include first set of conductive wireelectrodes 130, also referred to simply as first set of electrodes 130.First set of electrodes 130 can include any number of wire electrodes.For example, first set of electrodes 130 comprises first electrode 131,second electrode 132, third electrode 133, fourth electrode 134, fifthelectrode 135, and sixth electrode 136. In some cases, first electrode131, second electrode 132, third electrode 133, fourth electrode 134,fifth electrode 135, and sixth electrode 136 can be separate wires. Inother cases, first electrode 131, second electrode 132, third electrode133, fourth electrode 134, fifth electrode 135, and sixth electrode 136can be integrally formed as a single wire electrode.

It will be understood that for purposes of clarity, six electrodes areshown as comprising first set of electrodes 130 in the currentembodiment. In other embodiments, however, a set of electrodes couldcomprise any other number of electrodes.

In a similar manner, conductive wire electrodes 104 can compriseadditional sets of electrodes that are spaced apart in the longitudinaldirection. For example, in the current embodiment, composite 100 canalso comprise second set of electrodes 140 and third set of electrodes142. Additionally, composite 100 can comprise additional sets ofelectrodes.

Each set of electrodes may be spaced apart in the longitudinaldirection. In some cases, adjacent sets of electrodes may have oppositepolarities. For example, first set of electrodes 130 may be associatedwith a positive polarity, second set of electrodes 140 may be associatedwith a negative polarity and third set of electrodes 142 may beassociated with a positive polarity. This alternating arrangement cancontinue along the length of composite 100. As voltages are applied tothese electrodes with opposite polarities, actuating fibers 102 mayextend and/or contract.

In some embodiments, the ends of electrodes may be associated with aconductive member that provides electricity to one or more sets ofelectrodes. A conductive member could comprise any material that iscapable of conducting electricity. In some cases, a conductive membercould comprise a similar conductive material to the conductive wireelectrodes. In other cases, however, a conductive member could comprisea different type of conducting material from the conductive wireelectrodes. Moreover, in some cases a conductive member could comprise aconductive strip. In other cases, a conductive member could be aconductive wire.

For example, in one embodiment, the ends of electrodes associated with apositive polarity could be attached to a first conductive member whilethe ends of electrodes associated with a negative polarity could beattached to a second conductive member. The first and second conductivemembers could then be fastened to opposing sides of composite 100. Thefirst conductive member and the second conductive member may be furtherassociated with other electrical devices, components or systems. Withthis arrangement, conductive wire electrodes 104 may be in electricalcommunication with other components, systems or devices via theconductive members. An example of attaching conductive wire electrodesof an active fiber composite to a conductive member is described inWhinnery, U.S. Patent Application Publication Number 2010/0227521, nowU.S. patent application Ser. No. 12/397,695, filed on Mar. 3, 2009, theentirety of which is hereby incorporated by reference. This referencemay be hereby referred to throughout the remainder of this detaileddescription as the “active fiber composite case”.

Woven active fiber composite 100 may include provisions for associatingconductive wire electrodes 104 with actuating fibers 102 in a mannerthat enhances actuation of actuating fibers 102. In some embodiments,conductive wire electrodes 104 may be laid across a top surface ofcomposite 100. In other embodiments, conductive wire electrodes 104 maybe laid across a bottom surface of composite 100. In an exemplaryembodiment, conductive wire electrodes 104 may be woven betweenactuating fibers 102 in a manner that facilitates enhanced actuation byincreasing the contact area between actuating fibers 102 and conductivewire electrodes 104.

Generally, conductive wire electrodes 104 can be woven with actuatingfibers 102 in any known manner. Examples of different weaving patternsthat could be used include any three-dimensional weaves known in theart. It should be understood that while the current embodimentillustrates a particular weaving configuration for conductive wireelectrodes 104, other embodiments are not limited to a particular typeof weaving configuration. Details of the weaving configuration arediscussed in detail below.

A three-dimensional woven active fiber composite may include additionalprovisions to increase strength. In some embodiments, a woven activefiber composite may include filler fibers to add structural strength tothe woven active fiber composite. In some embodiments, filler fibers maybe disposed between adjacent pairs of conductive wire electrodes. Insome cases, filler fibers may be woven through actuating fibers of awoven active fiber composite. With this arrangement, the filler fibersmay strengthen the woven active fiber composite and also assist inmaintaining the desired spacing between adjacent pairs of conductivewire electrodes as well as actuating fibers.

As seen in FIGS. 1 through 3, composite 100 may include plurality offiller fibers 150, hereby referred to simply as filler fibers 150. Forpurposes of clarity, filler fibers 150 are shown in phantom in thecurrent embodiment. Generally, filler fibers associated with a wovenactive fiber composite may be electrical insulators. For example, insome embodiments, filler fibers may be constructed from fiber glass,including, but not limited to, S-glass and E-glass. In otherembodiments, filler fibers may be constructed from another electricallyinsulating material that can withstand sintering temperatures between1000 and 1500 degrees Celsius.

In different embodiments, a woven active fiber composite may includevarying numbers of filler fibers. In some embodiments, varying numbersof filler fibers may be disposed between adjacent pairs of conductivewire electrodes. In other embodiments, a constant number of fillerfibers may be disposed between adjacent pairs of conductive wireelectrodes.

In one embodiment, woven active fiber composite 100 may be configuredwith twelve filler fibers disposed between adjacent sets of electrodes.For example, in the current embodiment, first filler fiber 151, secondfiller fiber 152, third filler fiber 153, fourth filler fiber 154, fifthfiller fiber 155, sixth filler fiber 156, seventh filler fiber 157,eighth filler fiber 158, ninth filler fiber 159, tenth filler fiber 160,eleventh filler fiber 161 and twelfth filler fiber 162 (see FIG. 3) aredisposed between first set of electrodes 130 and second set ofelectrodes 140. In addition, twelve filler fibers are disposed betweenadjacent sets of electrodes along the length of composite 100.

In some embodiments, filler fibers 150 may be woven through actuatingfibers 102. Generally, filler fibers 150 may be woven through actuatingfibers 102 in any manner known in the art. Examples of different weavingpatterns that could be used include any three-dimensional weaves knownin the art. It should be understood that while the current embodimentillustrates a particular weaving configuration for filler fibers 150,other embodiments are not limited to a particular type of weavingconfiguration. Details of the weaving configuration are discussed indetail below.

FIG. 4 illustrates an embodiment of a weaving configuration for firstset of electrodes 130. In some cases, the remaining sets of electrodesmay also be configured in a similar weaving pattern. In otherembodiments, however, the weaving pattern could vary between differentsets of electrodes. Moreover, different weaving patterns could beselected according to desired electrical actuation properties, desiredcomposite geometry, desired composite strength as well as other featuresor characteristics associated with a three-dimensional woven activefiber composite.

Referring to FIG. 4, each wire electrode of first set of electrodes 130is woven in an alternating manner between two groups of actuatingfibers. As an example, first electrode 131 is woven in an alternatingmanner between actuating fibers in first group of actuating fibers 120and actuating fibers in second group of actuating fibers 122. In asimilar manner, second electrode 132 is also woven in an alternatingmanner between actuating fibers in first group of actuating fibers 120and actuating fibers in second group of actuating fibers 122. Inaddition, third electrode 133 and fourth electrode 134 are woven in analternating manner between actuating fibers in second group of actuatingfibers 122 and actuating fibers in third group of actuating fibers 124.Fifth electrode 135 and sixth electrode 136 are woven in an alternatingmanner between actuating fibers in third group of actuating fibers 124and fourth group of actuating fibers 126.

This woven arrangement provides contact between an electrode andactuating fibers from two adjacent groups of actuating fibers that areseparated in the vertical direction. However, it should be understoodthat this woven arrangement is only intended to be exemplary and inother embodiments other woven arrangements could be used. In variousdifferent woven arrangements, one or more electrodes can extend in thevertical and lateral directions in order to wrap around actuating fibersthat are spaced apart in both the vertical and lateral directions.

In some embodiments, one or more electrodes can be arranged into anelectrode mat. The term “electrode mat” as used throughout this detaileddescription and in the claims refers to a planar-like arrangement ofwire electrodes that extends in both the lateral and verticaldirections. In different embodiments, an electrode mat can havedifferent woven topologies that are determined by the electrode weavingpattern in the vertical and lateral directions. In some cases, eachelectrode mat can behave as a single electrode with either a positive ornegative polarity. Moreover, a woven active fiber composite can includemultiple electrode mats that are spaced apart from one another in thelongitudinal direction which behave as electrodes of alternatingpolarity.

In the exemplary embodiment, first set of electrodes 130 may beconfigured as a single electrode mat 180. Electrode mat 180 comprises awoven arrangement of electrodes that are approximately coplanar. Inaddition, electrode mat 180 extends in the lateral and verticaldirections of composite 100. In a similar manner, each set of electrodesalong the length of composite 100 may be configured as an electrode mat.

FIG. 5 illustrates an isometric view of an embodiment of composite 100.Referring to FIG. 5, first set of electrodes 130 and second set ofelectrodes 140 comprise substantially similar electrode configurations.In particular, the electrodes of first set of electrodes 130 and secondset of electrodes 140 comprise substantially similar weaving patterns inwhich each electrode is alternately woven between actuating fibers ofadjacent groups of actuating fibers, which are spaced apart in thevertical direction. Moreover, first set of electrodes 130 is configuredas electrode mat 180 and second set of electrodes 140 is configured aselectrode mat 182. In the exemplary embodiment, electrode mat 182 has asubstantially similar topology to electrode mat 180. In other words, theweaving pattern of electrodes is substantially similar for electrode mat180 and electrode mat 182. In a similar manner, the remaining sets ofelectrodes that are spaced apart along the length of composite 100 maybe arranged as substantially similar electrode mats of alternatingpolarities. In other words, the electrode configuration described abovefor first set of electrodes 130 may be repeated at each set ofelectrodes within composite 100. This substantially uniform pattern ofelectrodes helps improve actuation by improving symmetry along thelength of composite 100.

FIG. 6 illustrates an embodiment of a weaving configuration forplurality of filler fibers 150. Although only two filler fibers arevisible, in some cases the remaining filler fibers may also beconfigured in a similar weaving pattern. In other embodiments, however,the weaving pattern could vary between different filler fibers.Moreover, different weaving patterns could be selected according todesired composite geometry, desired composite strength as well as otherfeatures or characteristics associated with a three-dimensional wovenactive fiber composite.

Referring to FIG. 6, first filler fiber 151 is woven through the entireheight of composite 100 from first group of actuating fibers 120 tofourth group of actuating fibers 126 in an alternating manner. This isin contrast to the weaving configuration for the electrodes, which arewoven between two adjacent groups of actuating fibers. In a similarmanner, second filler fiber 152 is woven through composite 100 in analternating manner between actuating fibers of first group of actuatingfibers 120 and fourth group of actuating fibers 126. Moreover, firstfiller fiber 151 and second filler fiber 152 are woven in reversedirections. In particular, first filler fiber 151 starts at first upperedge 602 of composite 100 and ends at second lower edge 608 of composite100 while second filler fiber 152 starts at first lower edge 604 ofcomposite 100 and ends at second upper edge 606 of composite 100.

This woven arrangement provides contact between a filler fiber andactuating fibers from two different groups of filler fibers that areseparated in the vertical direction. However, it should be understoodthat this woven arrangement is only intended to be exemplary and inother embodiments other woven arrangements could be used. In otherembodiments, for example, filler fibers may be not woven through theentire height of a composite. In various different woven arrangements,one or more filler fibers can extend in the vertical and lateraldirections in order to wrap around actuating fibers that are spacedapart in both the vertical and lateral directions.

In some cases, the weaving of filler fibers 150 can increase thestructural strength of woven active fiber composite 100. In particular,filler fibers 150 can reduce the potential of buckling betweenconductive wire electrodes 104 of actuating fibers 102. With thisconfiguration, filler fibers 150 can help maintain the alignment ofactuating fibers 102 in the axial direction. In addition, in some cases,the weaving of filler fibers 150 may also assist in maintaining thelateral spacing between adjacent actuating fibers 102.

FIG. 7 illustrates a cross-sectional view of an embodiment of a portionof a woven active fiber composite. In particular, FIG. 7 illustrates across-sectional view of actuating fiber 701 and actuating fiber 702 ofcomposite 100 for purposes of describing the sizes and shapes ofactuating fibers 102, conductive wire electrodes 104, and filler fibers150.

In some embodiments, the sizes and/or shapes of actuating fibers andconductive wire electrodes may vary. In some cases, varying the sizesand/or shapes of actuating fibers and conductive wire electrodes maymodify the feature size of an electrode pattern. Using smaller electrodefeature sizes may provide for increased robustness for a woven activefiber composite, especially over traditional active fiber compositedesigns that have a minimum electrode feature size. In other cases,modifying the sizes and/or shapes of actuating fibers and conductivewire electrodes may allow for different structural properties for thewoven active fiber composite.

Actuating fibers 102 can have any size. In particular, the length anddiameter of actuating fibers 102 can vary. In the current embodiment,only a portion of the length of actuating fibers 102 is illustrated.However, it should be understood that actuating fibers 102 could haveany length necessary for constructing a woven active fiber composite ofa particular length.

Generally, actuating fibers 102 may have any cross-sectional shape.Examples of different cross-sectional shapes include, but are notlimited to: squares, rectangles, circles, triangles, regular shapes,irregular shapes as well as any other shapes. In this exemplaryembodiment, actuating fibers 102 may be associated with a generallycircular cross-sectional shape (see FIG. 6).

Referring to FIG. 7, in this embodiment, actuating fibers 102 may beassociated with diameter D1. Generally, diameter D1 can have any value.In some embodiments, diameter D1 may have a value in the range of 10micrometers to 200 micrometers. In other embodiments, diameter D1 mayhave a value in the range of 50 micrometers to 150 micrometers.

In different embodiments, the shape of conductive wire electrodes 104can also vary. In some embodiments, conductive wire electrodes 104 canhave any cross-sectional shape that has been previously discussed foractuating fibers 102. In an exemplary embodiment, conductive wireelectrodes 104 may have a generally circular cross-sectional shape.

In different embodiments, the size of conductive wire electrodes 104 canalso vary. In particular, the length and diameter of conductive wireelectrodes 104 can vary. In one embodiment, conductive wire electrodes104 may be associated with diameter D2. Generally, diameter D2 can haveany value. In some embodiments, diameter D2 may have a value in therange of 1 micrometer to 200 micrometers. In other embodiments, diameterD2 may have a value in the range of 5 micrometers to 25 micrometers.

In some embodiments, the spacing between adjacent sets of conductivewire electrodes can vary. In some cases, the spacing between adjacentsets of conductive wire electrodes may be irregular. In other cases, thespacing between adjacent sets of conductive wire electrodes may beregular. In an exemplary embodiment, adjacent sets of conductive wireelectrodes may be evenly spaced. This arrangement may help to createsubstantially uniform electromagnetic fields for interacting withactuating fibers. Additionally, this arrangement may help create an evenweave pattern that facilitates substantially uniform composite strengthover the entirety of a woven active fiber composite.

Referring back to FIG. 5, adjacent sets of conductive wire electrodes104 may be spaced apart by spacing S1. In some embodiments, the value ofspacing S1 may be in the range between 5 and 500 micrometers. In otherembodiments, the value of spacing S1 may be in the range between 100 and200 micrometers.

In different embodiments, the shape of filler fibers 150 can vary. Insome embodiments, filler fibers 150 can have any cross-sectional shapethat has been previously discussed for actuating fibers 102. In someembodiments, filler fibers 150 and conductive wire electrodes 104 mayhave different cross-sectional shapes. In other embodiments, fillerfibers 150 and conductive wire electrodes 104 may have substantiallysimilar cross-sectional shapes. Referring to FIG. 7, in the exemplaryembodiment, filler fibers 150 and conductive wire electrodes 104 areconfigured with generally circular cross-sectional shapes.

In an exemplary embodiment, filler fibers 150 may be associated withdiameter D3. In some cases, diameter D3 may be smaller than diameter D2that is associated with conductive wire electrodes 104. In other cases,diameter D3 may be larger than diameter D2. In one embodiment, diameterD2 of conductive wire electrodes 104 may be substantially similar todiameter D3 of filler fibers 150. With substantially similar diametersand cross-sectional shapes, conductive wire electrodes 104 and fillerfibers 150 may present a generally flat outer surface for woven activefiber composite 100.

Generally, the size of a contact region between an actuating fiber and awoven conductive wire electrode can be varied by changing the diametersof the actuating fibers and/or the conductive wire electrodes as well asother features of the geometry. In some cases, the size of the contactregion can be decreased. In other cases, the size of the contact regioncan be increased. In an exemplary embodiment, the size of the contactregion can be increased to allow for near-continuous contact between theconductive wire electrode and the actuating fiber by virtue of the woventopology.

In some embodiments, a woven active fiber composite may includeactuating fibers with periodically varying diameters. By varying thediameters of the actuating fibers periodically, conductive wireelectrodes and filler fibers may be applied at period minimums of theactuating fibers diameters. In some cases, this may help present agenerally flat outer surface for a woven active fiber composite.Examples of actuating fibers with periodically varying diameters aredescribed in the active fiber composite case.

By weaving conductive wire electrodes 104 with actuating fibers 102 andfiller fibers 150, various desirable features for an active fibercomposite can be achieved in an efficient manner. For example, the wovenconfiguration described in the embodiments helps to provide a highlyuniform spacing between adjacent electrode sets. In addition, theelectrode sets may be configured as electrode mats that are highlyplanar in order to achieve a high degree of symmetry along the activefiber composite. Moreover, using the woven arrangement helps to achievea high level of parallelism between adjacent electrode mats. Each ofthese features can facilitate increased actuation efficiency for anactive fiber composite.

In the embodiments discussed above and shown in the Figures, activefiber composite 100 is approximately straight. In some cases, actuatingfibers 102 can be maintained in a substantially straight configurationby tuning the weaving configuration. In other cases, however, actuatingfibers 102 could be arranged in a curved configuration by tuning theweaving configuration. In other words, the woven nature of composite 100allows for the creation of both straight and curved geometries for athree-dimensional woven active fiber composite. The geometry can bevaried by adjusting the weaving pattern accordingly.

FIG. 8 illustrates an isometric view of another embodiment of composite800. FIG. 9 illustrates a cross-sectional view of an embodiment ofcomposite 800. Referring to FIGS. 8 and 9, composite 800 includesactuating fibers 802 as well as conductive wire electrodes 804. Inparticular, conductive wire electrodes 804 may be woven betweenactuating fibers 802 in a substantially similar manner to the embodimentdiscussed above. Additionally, composite 800 can include filler fibers850 that are woven between actuating fibers 802 and help to reinforcecomposite 800.

A three-dimensional woven active fiber composite can include provisionsto help prevent actuating fibers from separating. In some cases, asleeve member can be used to provide containment of the actuating fibersin the lateral and vertical directions. In some cases, a sleeve membercan provide compressive containment of the actuating fibers in thelateral and vertical directions. In one embodiment, a sleeve member maybe wrapped around an outer periphery of a composite.

Composite 800 can further be associated with sleeve member 890. Sleevemember 890 may be configured to wrap around the outermost edges ofcomposite 800. In particular, inner surface 892 is configured to contactlower edge 831, first lateral edge 832, upper edge 833, and secondlateral edge 834 of composite 800. Lower edge 831, first lateral edge832, upper edge 833, and second lateral edge 834 may comprise outerperiphery 870 of composite 800. This arrangement helps to confinecomposite 800 in the lateral and vertical directions.

Generally, the length of sleeve member 890 can vary in differentembodiments. In some cases, sleeve member 890 may extend along theentire length of composite 800. In other cases, sleeve member 890 maycover only some portions of composite 800 in the longitudinal direction.

Sleeve member 890 can have any material properties. In some cases,sleeve member 890 may be substantially flexible. In some cases, sleevemember 890 may be substantially elastic. In other cases, sleeve member890 could be rigid to provide rigid support to composite 800 in thevertical and lateral directions.

For purposes of description, the term “radial direction” is usedthroughout this detailed description and in the claims to refer to anydirection that is perpendicular to the longitudinal or axial direction.For example, the radial direction in the current embodiment is anydirection perpendicular to an axial line extending through the center ofa composite. Moreover, the term “radial outward direction” is associatedwith any direction directed radially from an axial centerline towards anouter portion of a composite. Likewise, the term “radial inwarddirection” is associated with any direction directed radially from anouter portion of a composite towards an axial centerline.

Referring to FIGS. 8 and 9, sleeve member 890 may provide compressivecontainment in the radial direction. In particular, sleeve member 890applies a compressive force that is directed radially inward from sleevemember 890 towards axial center line 860. This compressive force acts toprevent any separation of composite 800 in the radially outwarddirection. It will be understood that as the compressive force actsradially inward, the compressive force will also prevent any separationof composite 800 in the lateral and vertical directions. Using thisconfiguration, sleeve member 890 helps to retain the cross-sectionalshape of composite 800 while still allowing stroke and actuation ofactuating fibers 802 in the axial direction. This arrangement may helpreduce or eliminate the need to fill composite 800 with a resin.

Although the current embodiment illustrates a sleeve member that issubstantially continuous, the properties of a sleeve member could varyin other embodiments. For example, in another embodiment, a sleevemember can be a mesh sleeve. In other embodiments, one or more holes,slots, or other features could be provided in the surface of a sleevemember. Furthermore, while the current embodiment illustrates a sleevemember with an approximately rectangular cross-sectional shape, in otherembodiments a sleeve member could have any other cross-sectional shapethat conforms to the cross-sectional shape of an associated composite.

Three-dimensional woven active fiber composites can be manufactured withany three-dimensional cross-sectional shape. In particular, while theprevious embodiments illustrate composites with approximatelyrectangular cross-sectional shapes, in other embodiments active fibercomposites can be manufactured with any other cross-sectional shapesincluding, but not limited to: rectangular, square, triangular, rounded,oval, circular, star, pentagon, hexagon, as well as any polygonal shapesor any other kind of cross-sectional shapes. Moreover, thecross-sectional shape could be regular or irregular. In addition, inembodiments including a sleeve member, the sleeve member could have asubstantially similar cross-sectional shape to match the cross-sectionalshape of the composite.

FIGS. 10 through 12 illustrate exemplary embodiments of differentcross-sectional shapes for a three-dimensional woven active fibercomposite. Referring to FIG. 10, composite 1000 has an approximatelycircular cross-sectional shape. In particular, actuating fibers 1002 arewoven together using electrodes 1004 and filler fibers in a manner toprovide an approximately circular outer edge 1010. In addition, sleevemember 1090 also has an approximately circular cross-sectional shape.Referring to FIG. 11, composite 1100 has an approximately star-likecross-sectional shape. In particular, actuating fibers 1102 are woventogether using electrodes 1104 and filler fibers in a manner to providean approximately star shaped outer edge 1110. In addition, sleeve member1190 also has an approximately star-like cross-sectional shape.Referring to FIG. 12, composite 1200 has an approximately hexagonalcross-sectional shape. In particular, actuating fibers 1202 are woventogether using electrodes 1204 and filler fibers in a manner to providesan approximately hexagon shaped outer edge 1210. In addition, sleevemember 1290 also has an approximately hexagonal cross-sectional shape.By manufacturing a three-dimensional woven active fiber composite tohave various different cross-sectional shapes, the composite may be usedin a variety of different situations that require actuators of differentgeometries.

In some embodiments, a composite could have a geometry with one or morehollow sections. For example, referring to FIG. 13, composite 1300 hasan approximately annular cross-sectional shape. In particular, actuatingfibers 1302 are woven together using electrodes 1304 and filler fibersin a manner to provide an approximately circular outer edge 1310. Inaddition, outer sleeve member 1390 also has an approximately circularcross-sectional shape. Also, composite 1300 has a hollowed out centralportion 1330, which has an approximately circular cross-sectional shape.In some cases, hollowed out central portion 1330 provides a hollowregion where no actuating fibers, filler fibers or electrodes arepresent. Moreover, in some cases, central portion 1330 can be reinforcedusing an inner sleeve member 1392. Referring to FIG. 14, composite 1400has an approximately rectangular cross-sectional shape. In particular,actuating fibers 1402 are woven together using electrodes 1404 andfiller fibers in a manner to provide an approximately rectangular outeredge 1410. In addition, outer sleeve member 1490 also has anapproximately rectangular cross-sectional shape. Also, composite 1400has a hollowed out central portion 1430, which has an approximatelyrectangular cross-sectional shape. In some cases, hollowed out centralportion 1430 provides a hollow region where no actuating fibers, fillerfibers or electrodes are present. Moreover, in some cases, centralportion 1430 can be reinforced using an inner sleeve member 1492. Byusing a hollowed cross sectional shape, the weight of a composite can bereduced. Moreover, using hollowed out shapes may provide for increasedadaptability of a composite to different components with varyinggeometries.

In still other embodiments, any cross sectional shapes could be used andmay include hollowed out central portions of a variety of differentcross sectional shapes. In some cases, the hollow central portion couldhave a different cross-sectional shape than the cross-sectional shape ofthe whole composite. For example, one embodiment can include a compositewith a rectangular cross-sectional shape and a hollow central portionwith a circular cross sectional shape.

Although the current embodiments illustrate various cross-sectionalshapes for a composite that are constant along the length of acomposite, in other embodiments it will be understood that a compositecould have varying cross-sectional shapes along the length of thecomposite. For example, the cross-sectional shape could vary betweenrounded and rectangular cross-sectional shapes. The woven nature of theactive fiber composites allows for a wide variety of different compositegeometries that can be easily created to meet the specific geometricrequirements of a given system where an actuating composite is used.

A three-dimensional woven active fiber composite can be manufacturedusing any known processes for manufacturing three-dimensional wovencomposites as well as processes known for manufacturing active fibercomposites. An exemplary method for manufacturing a two dimensionalwoven active fiber composite is described in the active fiber compositecase. In some cases, for manufacturing a three-dimensional woven activefiber composite, the manufacturing steps could be substantially similarto the method used for the two dimensional case, with the step ofweaving actuating fibers with electrodes and/or filler fibers modifiedto incorporate three-dimensional weaving configurations for theelectrodes and/or filler fibers. However, in other cases, any methodsknown in the art can be used.

Additionally, a composite could be manufactured to have any length. Insome cases, the composite may be manufactured with a predeterminedlength, while in other cases the composite could be manufactured as abulk composite that may be cut to a desired size depending on theapplication of the composite material. In some cases, a compositeportion could be cut from a bulk composite before sintering. In othercases where sintered PZT fibers are used, a composite portion could becut from a bulk composite after sintering.

While various embodiments of the invention have been described, thedescription is intended to be exemplary, rather than limiting and itwill be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible that are within the scopeof the invention. Accordingly, the invention is not to be restrictedexcept in light of the attached claims and their equivalents. Also,various modifications and changes may be made within the scope of theattached claims.

What is claimed is:
 1. A woven active fiber composite, comprising: a longitudinal direction extending along a length of the woven active fiber composite; a lateral direction extending along a width of the woven active fiber composite; a vertical direction extending along a height of the woven active fiber composite; a plurality of actuating fibers, each actuating fiber extending in the longitudinal direction and having a generally circular cross-sectional shape associated with a first diameter; a first group of actuating fibers from the plurality of actuating fibers that are spaced apart from one another in the lateral direction; a second group of actuating fibers from the plurality of actuating fibers that are spaced apart from one another in the lateral direction; the second group of actuating fibers being spaced apart from the first group of actuating fibers in the vertical direction; a conductive wire electrode configured to transfer electrical energy to and from the first group of actuating fibers and the second group of actuating fibers, the conductive wire electrode having a generally circular cross-sectional shape associated with a second diameter; and wherein the conductive wire electrode is in contact with at least one actuating fiber from the first group of actuating fibers and wherein the conductive wire electrode is in contact with at least one actuating fiber from the second group of actuating fibers.
 2. The woven active fiber composite according to claim 1, wherein the first diameter is larger than the second diameter.
 3. The woven active fiber composite according to claim 1, wherein the first diameter is from 10 micrometers to 200 micrometers.
 4. The woven active fiber composite according to claim 3, wherein the first diameter is from 50 micrometers to 150 micrometers.
 5. The woven active fiber composite according to claim 1, wherein the second diameter is from 1 micrometer to 200 micrometers.
 6. The woven active fiber composite according to claim 5, wherein the second diameter is from 5 micrometers to 25 micrometers.
 7. The woven active fiber composite according to claim 1, further comprising at least one filler fiber woven between the plurality of actuating fibers.
 8. The woven active fiber composite according to claim 7, wherein the at least one filler fiber has a generally circular cross-section associated with a third diameter.
 9. The woven active fiber composite according to claim 8, wherein the third diameter is substantially similar to the second diameter.
 10. The woven active fiber composite according to claim 1, wherein the first diameter periodically varies along the longitudinal direction of the plurality of actuating fibers.
 11. A woven active fiber composite, comprising: a longitudinal direction extending along a length of the woven active fiber composite; a lateral direction extending along a width of the woven active fiber composite; a vertical direction extending along a height of the woven active fiber composite; a plurality of actuating fibers extending in the longitudinal direction, at least one actuating fiber of the plurality of actuating fibers having a generally circular cross-sectional shape associated with a first diameter; the plurality of actuating fibers being spaced apart in the lateral direction and the vertical direction; a plurality of conductive wire electrodes configured to transfer electrical energy to and from the plurality of actuating fibers, each conductive wire electrode of the plurality of conductive wire electrodes having a generally circular cross-sectional shape associated with a second diameter; and wherein a first set of conductive wire electrodes are woven in a planar configuration between the plurality of actuating fibers, the planar configuration of conductive wire electrodes extending in the lateral direction and the vertical direction.
 12. The woven active fiber composite according to claim 11, wherein the second diameter is smaller than the first diameter.
 13. The woven active fiber composite according to claim 11, wherein a second set of conductive wire electrodes are woven in a planar configuration between the plurality of actuating fibers, the planar configuration of conductive wire electrodes extending in the lateral direction and the vertical direction and wherein the first set of conductive wire electrodes is spaced apart from the second set of conductive wire electrodes in the longitudinal direction.
 14. The woven active fiber composite according to claim 13, wherein the first set of conductive wire electrodes are spaced apart from the second set of conductive wire electrodes from 5 micrometers to 500 micrometers.
 15. The woven active fiber composite according to claim 13, wherein the first set of conductive wire electrodes are spaced apart from the second set of conductive wire electrodes from 100 micrometers to 200 micrometers.
 16. The woven active fiber composite according to claim 13, wherein the plurality of conductive wire electrodes includes at least three sets of conductive wire electrodes, each set of conductive wire electrodes are woven in a planar configuration between the plurality of actuating fibers, the planar configuration of each set of conductive wire electrodes extending in the lateral direction and the vertical direction; and wherein adjacent sets of conductive wire electrodes are spaced apart from each other in the longitudinal direction.
 17. The woven active fiber composite according to claim 16, wherein adjacent sets of conductive wire electrodes are evenly spaced.
 18. The woven active fiber composite according to claim 13, further comprising at least one filler fiber woven between the plurality of actuating fibers; and wherein the at least one filler fiber is disposed between the first set of conductive wire electrodes and the second set of conductive wire electrodes.
 19. The woven active fiber composite according to claim 18, wherein the at least one filler fiber has a generally circular cross-section associated with a third diameter.
 20. The woven active fiber composite according to claim 19, wherein the third diameter is substantially similar to the second diameter. 